附錄3
外文文獻
Design of Movable Gantry CNC Milling Machine
ZHANG Jian
Abstract: this paper describes the nc milling roller, the overall design and analyses the bilateralsuper-modulus gear pair of driving mechanism of the main points of design,installationguidesurface of the X axis is introduced in this paper
Keywords: mobile nc milling design
This machine is mainly used for metal parts of the plane and inclined plane work. It has enough rigidity, Milling head adopts milling head in Taiwan, Milling head with flexible, Spindle motor is frequency conversion motor. It can undertake stepless speed, Ensure accuracy of machine tools and machining precision has good stability, This machine is of high efficiency and exercise,For convenience, make the drive more reliable and convenient in maintenance, less consumption, beautiful modelling, etc, widely used in mechanical manufacturing industry.
This paper described the mobile CNC milling refers to longmen framework Vertical milling movement. The biggest advantage of milling roller is (1) Machine cover an area of an area small. Workbench mobile Longmen milling machine, complete machine must be higher than vertical stroke length two times. However, Workbench mobile Longmen milling machine, The length of side frame which is fabricated according to add only longitudinal travel width, The dynamic response of the machine is good. Workbench mobile Longmen milling machine adopts fixed table. The whole cast out with bed, Longmen framework of longitudinal motionDrive torque equivalent unchanged, It is not because of bearing the weight of the workpiece changesChange, so as to ensure the accuracy and performance of the machine tool.
The independent design mobile nc Longmen milling（FIG 1）has been a special machine to use. It can satisfy the large castings, steel parts boring and milling, drilling, etc multiple operation process. It is right milling head, It also can process the 4 side of workpiece. The goal of the main design parameters such as Longmen milling under: workbench area 1800mm × 4000mm, The travel for X axis:4000mm The travel for Y axis:2000mm The travel forZ axis:750mm, Spindle power 18.5KW, Each axis rapid federate 10m/min.
Figure 1 Mobile nc milling
1. Mechanical parts design
The bed include Bed, Slide, Longmen frame spindle box, Three axis to drive mechanical parts and related CNC servo part, Now ,The design process is emphasized as follows: The bed is the basic design work, The size of the bed of the design affects the complete machine design. And the rationality of the design of directly affect the whole Machine stiffness. The cross-section shape for the bed like ∏,(FIG 2) The plane is working on a bed of mesa design has 9 T shaped groove. For the convenience of bed and working mesa of pure dig imageT processing, groove tank completely, The right and left two concerning the design has a long narrow swing plane. It is used to linear rolling guide vice, The author put rail surface design in the two side bed. The main consideration of force transmission directions and unloading, Because the bed will be dragon framework of gravity, cutting force and the gravity of the workpiece, This design can directly into the gravity of longmen framework to machine tools, and Bed only suffer the gravity of the workpiece. The bed by the following basic wall thickness determine By the following formula.
C=1/4(2L+B+H)
Type: C,L,B is respectively for bed length, width and height of size and unit for the m.
Based on equivalent size c, Consulting relevant form，Take the basic wall thickness is 38mm，
Figure 2 Shape of concerning the cross-section
Spindle box adopts 300 mm × 300 mm section design. The torsion bending capacity are stronger. Spindle gearboxes USES two gears Gear sliding speed-change mechanism.
It can adapt rough machining requirements. Spindle unit adopts four supporting structure, Ahead three groups of Angle contact ball bearing used to withstand cutting force. Spindle end a deep groove ball bearings are used to unloading, That is not of the Sliding gears of the additional moment.
Longmen framework used integral frame which is fabricated according to the design concept, It took about beam and column design into a whole. Although make casting and assembly adjusting difficulty, the whole framework of longmen rigid better, more important is to slide have assembled spindle box, etc. Slide is designed in the frame which is fabricated according to the geometrical dimensions and spindle box, According to the center axis of the guide bar as far as possible to face for the principle, The Z axis and the driver installation position in design, effectively reduce the weight of the slide.
Designed to drive into the idea as follows, The X axis to drive
Use the bilateral super-modulus gear pair aggravating preloading linear rolling guide vice.X axis and Y axis uses big diameter ball screw preloading vice hardened guide. Rail sliding parts attached engineering plastics, It avoids low when crawling phenomenon, and guide the design is inclined with adjustable device. This machine design make the whole machine to coordinate performance. The axis of the feeding speed and force get the optimal matching.
Due to the longitudinal axis machine movement X, and is moving longmen framework of longmen framework weighed 10T, so the linear rolling guide rails to must choose.Because the ball rail system of small friction coefficient, very suitable for longmen framework of moving rigidity requirement.Guide the slider choose one type, each slide block dynamic load can achieve 10t. Considering the safety coefficient, every guide installation 2 slider. Longmen framework for the driver bilateral super-modulus gear pair (see chart 2), feed movement by 3 input, through two inclined gear motor shaft/and axis to 2, and then by two gear - and to drive rack. And thus promote longmen framew3 the helical gear axle spiral of the two opposite directions. Through the spring in the shaft on a three axial force F, make the helical gear trace of axial movement produced at 1 and 2 and axial shaft in the opposite direction Angle of small, round 4 and 5) respectively, the gear tooth surface with two rack, eliminate the gap.
1.2.3--- axis 4.5--- Rack
Figure 3 Bilateral super-modulus gear pair
Spindle box and vertical motion Z axis adopts ball screw assembly transmission. Because of this machine is not high speed milling machine, the Z axis of the feeding system for servo motor through the ratio of 4 for parallel axis set than gearbox drives the ball screw rotation. In the design of special attention to the Z axis of safety problems. First choose the servo motor with electromagnetic brake, second in the ball screw with a two-way overrunning clutch, prevent ball nuts rotation caused spindle box mechanical prolapse. Of course, in order to protect the z-axis feed institutions, but also in the accuracy with two balance on the slide cylinders. Balance Q, etcThe quality of parts in spindle box 85%.
Spindle box around move for the Y axis, in order to guarantee the precision Y axis, and only by their level of ball screw and axial force, servo motor and the ball screw straight league. The author selects the coupling with overload protection device, in the overload when coupling automatically.
2 Selection of CNC system
The Siemens numerical control system is adopted, because this system 840D provides longmen shaft synchronization function. Use this function, the machine can to dragons
Door frame for shaft (into) no, X2 clamps its X1 mechanical deviation of displacement. The actual value can exercise for comparison, even the smallest deviation can be corrected, and therefore improve the accuracy of the X axis movement
3 Epilogue
The author finally, according to the professional machine parts manufacturers to provide design samples design will reach the twice the result with half the effort. In The design process, the author of CNC system, spindle unit, gearbox, super-modulus gear and ball screw guide etc. According to the sample of empirical formulas, not only shorten design time, make the higher reliability. At the same time we must pay great attention to the timely design machine tools, such as the application of three-dimensional software components immediately after the establishment sketches for 3d model, through the assembly interference, machine avoid collisions occur when in assembly Wade rework phenomenon.
[翻譯]
移動式數(shù)控龍門銑床的總體設計
張堅
摘要：闡述了移動式數(shù)控龍門銑床的總體設計，并重點分析了雙邊齒輪齒條副驅動機構的設計要點，對X軸的導軌安裝面作了介紹。
關鍵詞：移動式 數(shù)控龍門 銑床設計
本文所述的移動式數(shù)控龍門銑床是指龍門框架作縱向移動的龍門銑床。移動式龍門銑床的最大優(yōu)點是：
（1）機床占地面積小。工作臺移動式龍門銑床，整機長度必須兩倍于縱向行程長度，而移動式龍門銑床的整機長度只需縱向行程加上龍門架側面寬度即可。
（2）機床的動態(tài)響應好。移動式龍門銑床采用的是固定工作臺，一般與床身整體鑄出，龍門框架縱向運動的驅動力矩等值不變，不會因工件的承載重量的改變而變化，從而保證了加工精度和機床的響應性能。筆者獨立設計的移動式數(shù)控龍門銑床（圖1），現(xiàn)已作為專機投入生產應用，能滿足大型鑄件、鋼件的鏜、銑、鉆等多工序加工；配上直角銑頭，還可對工件的個側面進行加工。由于設計思想正確，配套零部件質量過關，該機床各項指標均已達到數(shù)控龍門銑床相關國家標準的要求。該龍門銑床的主要設計參數(shù)如下：工作臺面積為1800mmX4000mm，X軸行程為4000mm，Y軸行程為2000mm，Z軸行程為750mm，主軸功率18.5KW，各軸快速進給為10m/min。
1.機械部分設計
整機分為床身、龍門架、滑臺、主軸箱、三軸進給驅動機構機械部分及相關數(shù)控伺服部分。現(xiàn)把設計過程中的重點闡述如下:
床身是本次設計工作的基礎，床身的尺寸設計影響著對整機的設計，而且設計的合理性直接影響到整機的剛度。床身的截面形狀為∏形（圖1）。床身的上平面即工作臺面設計有9條T形槽，為方便床身工作臺面和T形槽的精刨加工，槽完全貫通。床身的左、右兩下腳各設計有一個狹長平面，用來安放滾動直線導軌副。筆者把導軌面設計在床身的兩下側，主要是考慮力的傳遞方向與卸荷問題。因床身會受到龍門框架的重力、切削力和工件的重力，這樣的設計可使龍門框架的重力直接傳入到機床的基礎上，而床身只受到工件的重力。床身的基本壁厚由以下公式初定:
C=1/4(2L+B+H)
式中：L. B. H 分別為床身的長、寬、高尺寸，單位為m。根據(jù)當量尺寸C，查閱相關表格（ 略），取基本壁厚為38mm。
主軸箱采用.300mmX300mm 截面設計，其抗扭抗彎能力更強。主軸變速箱采用兩檔滑移齒輪變速機構，可適應粗精加工需求。主軸單元采用4支承結構，前面三組角接觸球軸承用來承受切削力，主軸尾部一個深溝球軸承用來卸荷，使主軸不受到滑移齒輪產生的附加力矩的影響。
龍門框架采用的是整體龍門架的設計概念，即把橫梁與左右立柱設計成一體，雖然使鑄造和裝配調整時的難度加大，但整體龍門框架的剛性更好，更重要的是使主軸箱、滑臺等部件有了裝配基準。
滑臺的設計是在龍門架和主軸箱的幾何尺寸確定后，按照主軸的中心盡量貼近橫梁上的導軌面為原則，并把Z軸驅動安裝位置設計在滑臺上，有效地減輕了滑臺的重量。
設計進給驅動機構的構思如下：X軸的進給驅動機構采用雙邊齒輪齒條副加重預壓滾動直線導軌副，Y軸與X軸采用大直徑預壓滾珠絲杠副加硬導軌副，且導軌滑動部分貼有工程塑料，避免低速時產生爬行現(xiàn)象，而且導軌部分設計有斜鑲條可調裝置。這樣設計使機床的整體進給性能得以協(xié)調，各軸的進給速度和進給力得到了最佳匹配。
由于機床的縱向運動X軸是龍門框架移動，而龍門框架重達10t，所以導軌必須選用直線滾動導軌。因為滾動導軌副的摩擦系數(shù)小，非常適合龍門框架移動的動靜剛度要求。導軌的滑塊選用加長加寬型，每個滑塊的動載荷可達到10t?？紤]到安全系數(shù)，每根導軌安裝3個滑塊。龍門框架的驅動源為雙邊齒輪齒條副（見圖3），進給運動由軸2輸入，通過兩對斜齒輪將運動傳給軸1和軸3，然后由兩個直齒輪4和5去傳動齒條，從帶動龍門框架移動。軸2上兩個斜齒輪的螺旋線的方向相反。通過彈簧在軸2上作用一個軸向力F，使斜齒輪產生微量的軸向移動，這時軸1和軸3便以相反的方向轉過微小的角度，使齒輪4和5分別與齒條的兩齒面貼緊，消除了間隙。
主軸箱的上下垂直運動Z軸采用滾珠絲杠副傳動。由于本機床不是高速銑床，Z軸的進給系統(tǒng)為伺服電動機通過傳動比為4的平行軸定比齒輪箱帶動滾珠絲杠旋轉。筆者在設計中特別注意Z軸的安全問題。首先選用帶電磁剎車的伺服電動機，其次在滾珠絲杠上裝有一雙向超越離合器，防止?jié)L珠螺母自轉引起主軸箱機械式下垂。當然，為了保護Z軸進給機構的精度，還在滑臺上裝有兩個平衡油缸。平衡力Q等于主軸箱部件質量的85%。
主軸箱的左右移動為Y軸,為了保證Y軸的傳動精度，并使絲杠只受水平軸向力，故采用伺服電動機與滾珠絲杠直聯(lián)方式。筆者選用的聯(lián)軸器帶有過載保護裝置，在過載時聯(lián)軸器會自動脫開。
2.數(shù)控系統(tǒng)選型
數(shù)控系統(tǒng)采用的是西門子840D，因為此系統(tǒng)提供了龍門軸的同步功能。使用此功能，本機床可以對龍門框架進給軸（X1，X2）實現(xiàn)無機械偏差的位移。運動的實際值可進行連續(xù)比較，即使最小的偏差也可以得到糾正，因此提高了X軸的運動精度。
3.結語
筆者最后要說明的是，根據(jù)專業(yè)機床零部件廠商提供的設計樣本進行設計會達到事半功倍的效果。在此次設計過程中，筆者對數(shù)控系統(tǒng)、主軸單元、變速箱、齒輪齒條和絲杠導軌等都按照樣本上的經驗公式得出，不僅大大縮短了設計時間，同時使設計的可靠性更高。同時在設計機床中要注重適時應用三維軟件，如在部件草圖確立后就應立即進行三維模型裝配，通過進行裝配干涉檢查，避免機床在裝配時出現(xiàn)的碰撞干涉返工現(xiàn)象。
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